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Commit 35ff6935 authored by Sonic Zhang's avatar Sonic Zhang Committed by Linus Torvalds
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Blackfin Serial Driver: handle irregular DMA register status in auto start mode 

This bug is caused by irregular behavior of DMA register CURR_X_COUNT
and CURR_Y_COUNT when an auto restart uart rx DMA run to last byte in
DMA buffer, trigger the interrupt and stay at this possiton. The status
of current x and y is 0:7 instead of 512:8 or 0:8. The driver doesn't
take care of this case when calculating the position.

URL: http://blackfin.uclinux.org/gf/tracker/5063


Reported-by: default avatarTomasz Motylewski <t.motylewski@bfad.de>

Signed-off-by: default avatarSonic Zhang <sonic.zhang@analog.com>
Signed-off-by: default avatarMike Frysinger <vapier@gentoo.org>
Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f9d36da9

drivers/serial/bfin_5xx.c

+4 −3
Original line number Diff line number Diff line
@@ -490,7 +490,7 @@ void bfin_serial_rx_dma_timeout(struct bfin_serial_port *uart) 
	uart->rx_dma_nrows = get_dma_curr_ycount(uart->rx_dma_channel);

	x_pos = get_dma_curr_xcount(uart->rx_dma_channel);

	uart->rx_dma_nrows = DMA_RX_YCOUNT - uart->rx_dma_nrows;

	if (uart->rx_dma_nrows == DMA_RX_YCOUNT)

	if (uart->rx_dma_nrows == DMA_RX_YCOUNT || x_pos == 0)

		uart->rx_dma_nrows = 0;

	x_pos = DMA_RX_XCOUNT - x_pos;

	if (x_pos == DMA_RX_XCOUNT)
@@ -546,15 +546,16 @@ static irqreturn_t bfin_serial_dma_rx_int(int irq, void *dev_id) 
{

	struct bfin_serial_port *uart = dev_id;

	unsigned short irqstat;

	int pos;

	int x_pos, pos;



	spin_lock(&uart->port.lock);

	irqstat = get_dma_curr_irqstat(uart->rx_dma_channel);

	clear_dma_irqstat(uart->rx_dma_channel);



	uart->rx_dma_nrows = get_dma_curr_ycount(uart->rx_dma_channel);

	x_pos = get_dma_curr_xcount(uart->rx_dma_channel);

	uart->rx_dma_nrows = DMA_RX_YCOUNT - uart->rx_dma_nrows;

	if (uart->rx_dma_nrows == DMA_RX_YCOUNT)

	if (uart->rx_dma_nrows == DMA_RX_YCOUNT || x_pos == 0)

		uart->rx_dma_nrows = 0;



	pos = uart->rx_dma_nrows * DMA_RX_XCOUNT;